Reliability of isokinetic measurements of ankle dorsal and plantar flexors in normal subjects and in patients with peripheral neuropathy

Abstract

Objective: To establish a reliable method for evaluation of motor performance of ankle dorsal and plantar flexors in healthy subjects and in patients with peripheral neuropathy. Design: Thirty-eight control subjects and 7 patients with peripheral neuropathy were studied. All patients and 25 control subjects were tested twice. Patients and Control Subjects: An outdoor clinic sample of 7 patients with hereditary motor sensory neuropathy (HMSN) and 38 control subjects. Main Outcome Measures: The effect of a rest interval, a displacement of the axis of rotation, examination by three investigators on the peak torque and work of dorsal and plantar flexors, and the percentage difference at test-retests. Results: Control subjects had percentage differences of 5.6% and 8.0% for dorsal flexion and 3.8% and 8.7% for plantar flexion at 60°/sec and 180°/sec, respectively. In neuropathic patients the percentage differences were 0% and 8.6% for dorsal and 5.1% and 12.3% for plantar flexion at 30°/sec and 60°/sec, respectively. No interindividual differences between 3 investigators were found. A rest interval between trials resulted in an increased plantar flexion peak torque ( P < .05). Displacement of 1.5cm of the axis of rotation resulted in a change of the peak torque of 8.3% for plantar flexion ( P < .01). Conclusions: A well-defined test protocol for isokinetic motor performance of the ankle dorsal and plantar flexors provides a reliable procedure for quantification of motor function in healthy subjects and in patients with HMSN1.